Method and means for purifying lubricants



Feb. 9, 1943. P. MILLER ET AL I METHOD AND MEANS FOR PURIFYI NG LUBRICANTS Filed Dec. 31, 1937 (/I FIL TERED 0/4 l VLE T 7/1. 7 :72 to on.

Patented Feb. 9, E943 METHOD AND MEANS FOR PURI'FYING I LUBRICANTS Pharis Miller, Elizabeth, and Eugene Lieber,

Linden, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application December-s1, 1937, Serial No. 182,648

"17 Claims.

The present invention relates to methods and means for purifying lubricating oils while main.- taining therein a resistance to oxidation and decomposition during the period of their normal life. More specifically, this invention has to do the period of use.

accompanying drawing.

terial 5.

ture conditions.

like.

with supplying addition agents of various types it has been necessary to add an excess of the to lubricating oils to improve and preserve the inhibiting substances in order that the point at oils by maintaining therein an adequate con'cenwhich they have been completely consumed will tration of a substance capable of effecting resubstantially coincide with the point at which I sistance to oxidation and decomposition during the oil will normally be replaced. However, it Particularly, the invention has been known that such over-charging" of the deals with the use of addition agents which are oil with an inhibitor results in a tendency to aconly slightly soluble in the oils with which they celerate sludge formation in the oil, as indicated are used; and, further, the invention has to do y th r sults ta n d y m ans f the S ah with the treatment of lubricating oils, used in 1 test. On the other hand, if to avoid undue internal combustion engines, with small amounts sludge formation, the original quantity of added of difilcultly soluble addition agents added to the inhibitor is decreased it has been found that the oils while in service, and in successive increments oil is apt to deteriorate very rapidly during the as required. Included in the concept is the use latter portion of its normal period of use. Of of conventional oil filter systems to accomplish course the most desirable manner of adding inthe addition of the agents disclosed. hibiting substances to an oil would be to adjust The invention may be fully understood from such addition, in quantity and time, to the actual the following description and by reference to the condition of the oil, while in use.

as the inhibitor is consumed, more would be The filter shown isone such as is described in added and in the amount required. The difi'lthe-United States Patent 1,914,999 granted to cultles involved in devising such methods and George M, Maverick and George L. Matheson, means, however, have thus far prevented the decomprising an outer case I, an inner case 2, an oil velopment of any convenient system of accominlet line 3, adapted to admit oil to the inner case, pushing Such a Procedureand, concentric with the line 3, an oil outlet line NOW, according to h present invention. it is 4. As described in the above mentioned patent, proposed to utilize those substances previously the case 2 is filled with a fibrous or filamentous considered unsuitable for use as inhibiting agents, filter material 5 such as wool, asbestos, artificially because of their low solubility in oil, to accomprepared mineral or glass wool or other similar plish the desirable procedure of maintaining the material which has been previously impregnated resistance of oils to decomposition or oxidation or loaded with an inhibitor substance having only during use, without the necessity for overslight solubility in lubricating oils. The inhibcharging or for any complicated systems, meitor is shown in the drawing as particles 6 dishanical or otherwisepersed throughout the mass of the filter ma- There are available, a great number of ma- 40 terials which have been discovered to have a In use, lubricating oils and especially oils used beneficial action in retarding the decomposition for the lubrication of internal combustion enof oils in service, but which are only slightly solugines are required to withstand severe temperable in such oils even at the temperatures to which These conditions cause the the oils are raised during use. more or less rapid formation of decomposition or have prev ly been ar ed s unsuitable as oxidationproducts such as acids, sludge and the addition agents, by reason of their nature, but by The formation of such products has been thepresent invention they may be utilized with reduced, to some extent, by the use of addition i y nd en fi Among the materials now agents which inhibit oxidation of the oils and 'refound to be useful are included those substituted aromatic materials, having only slight solubility duce or delay sludge formation. While effective,

these agents have been found to be the source of other dimculties.

Most of the addition agents normally used are consumed rapidly in service, and, that they may be effective during the entire normal use of an oil,

In other words,

These substances at the operating temperatures of the oils', such as the sulfur-containing phenolic substitutes, and particularly the unalkylated materials such as diphenol-disulfide and diphenyl sulfide. In addition, the phenyl mercaptans and polysulfides are useful as well as the corresponding naphthol, anthrol and phenanthrol compounds. Such substances as sulfurized wood creosote, sulfurized cresols and thiophenylbetanaphylamine, may also be employed, as well as slightly oil soluble metallic soaps and other metallo-organic compounds for improving engine performance.

The technique of utilization of these agents, as now discovered is to provide a reservoir of the additive material through which will flow a considerable portion of oil drawn from the point or points of use and which oil is thereby renewed in its ability to resist oxidation and decomposition. Accordingly, renewal of the inhibitor content of the oil takes place automatically and in accordance with the particular requirements of the oil atany given time. Due to the nature of the inhibitor used, the oil is capable of dissolving only a certain amount at any degree of temperature and if the inhibitor content is at a maximum on entering the reservoir no further quantity can be dissolved. Likewise,'if the content is below a maximum the oil will then take up from the material in the reservoir such quan tities as will substantially effect saturation. In this fashion the resistance of the oil to decomposition is maintained at an optimum during its entire life without the overcharging formerly necessary and without causing either acceleration of sludge formation or sudden failure of the oil due to exhaustion of the-inhibitor substance.

Although the reservoir for the addition agent may be provided as a separateinstallation, it has been found to be most convenient to enlarge the function of the conventional oil filter assembly, now in common use, by utilizing its available reservoir capacity. Such filters as may be used in'this manner are well known in the art, including those types disclosed by United States Patents 2,071,529 and 2,071,550. Provision is made in such filters for a removable or a refillable cartridge of porous of fibrous material such as activated clay, cotton, asbestos or glass wool, or materials of the type described in United States Patent 1,914,999. In such adaptation of existing facilities the material comprising the of phenol sulfide were distributed through the waste as the filter was packed.

The filtered oils obtained from each run then subjected to the following tests:

1. The determination of lead tolerance by the Underwood method," and reported as a lead number for the oil, indicating the tendency of the oil to corrode metal.

2. The determination of color by means of the Tag-Robinson colorimeter.

3. The determination of acid number in accordance with the procedure set forth by A. S. T. M. test D-188-27T.

were

4. The determination of saponification number The result of these tests are reported in the following tabulation.

lest Original oil First run Second run 1. Less than 0 0. 010 0. 040+ 2. Color $4 3. 0. 83 0. 69 0. 56 4. Saponification No. 2. 9 l. 91 1.53 5. Co. of oxygen adsorbed. 133. 67 65, 50, 43

The lead number reported is a percentage figure indicating the amount by weight of lead oleate (calculated as lead oxide) which may be absorbed by an oil, in successive increments, before a metal against which it is discharged continuously, shows a loss of weight equal to milligrams. With a fresh oil a lead tolerance below 0.020 is considered unsatisfactory. Attention is directed therefore to the high lead tolerance of the used oil after filter treatment and contact with the type of inhibitor material disclosed. Comparison is also made with the lead tolerance of the oil subjected to filtering alone.

The foregoing description and the specific ex-v amples given are for the sole purpose of providcartridge may be loaded with fine particles of i of the material itself or of an inhibitor impreg-- nated material-may be disposed in the filter chamber in such manner as to be continuously contacted by oil passing through the chamber.

Proceeding in accordance with the disclosure as set' forth above, tests have been made to determine the effectiveness of the application of the system contemplated. These tests were made on two portionsof an oil comprising the drainings collected from the crankcases of a number of automobile engines. Each of the two portions used was circulated through a conventional type oil filter packed with cotton waste. The circu lation of each portion through the filter was continued for a period of three hours while maintaining on the oil, a pressure of 20 pounds per square inch and a temperature therein of 200 F. The system was cleaned between runs.

ing an understanding of the invention, which is not to be limited in any manner thereby, but only bythe appended claims in which it is intended to claim all novelty inherent in the invention, as broadly as the prior art permits.

We claim:

1. A method for maintaining and improving the quality of a lubricating oil during service comprising circulating at least a portion of said oil through an addition agent reservoir containing a supply of slightly oil-soluble improving agent in undissolved form having oxidation inhibiting properties, whereby said oil contacts at least a portion of said improving agent and dissolves a small amount thereof, and recirculating said treated oil into service.

2. A method for inhibiting oxidation of a lubricating oilin service comprising circulating suc-' cessive portions of said oil through a filter mechanism containing an oxidation inhibiting substance having a low limit of solubility in said oil, said inhibitor being in undissolved form so that it is gradually added to the oil as the oil circulates through the filter.

3. A method according to claim 2 in which the 1 inhibitor is a phenolic material.

phide.

4. A. method according to claim 2 in which the substance inhibiting oxidation is phenol disul- 5. A method according to claim 2 in which the inhibitor is-a substituted aromatic material.

6. A method according to' claim 2 in which the inhibitor is an aromatic sulphur compound.

7. A. method according to claim 2 in which the inhibitor is a metallo organic derivative.

8. A method according to claim 2 in which the inhibitor is an oil-improving metal soap.

.9. An article of manufacture for insertion into 'alubricating oil system for improving and maintaining the quality of lubricating oils during service which comprises a'nontainer provided with an inlet and an outlet for oil and containing between said inlet and outlet a supply of slightly oil-soluble improving agent in undissolved .formiwhich will dissolve sufliciently in the oil during service to inhibit decomposition thereof. 10. Ass. new article of manufacture, an oil filter for use in purifying and inhibiting oxide; tion and debomposition of internal combustion engine crankcase "lubricants during service, which comprises a container provided with an 'inletand an outlet for oil and containing. between said in:

dispersed therethrou h, particles of aslightlybilsoluble oxidation inhibitor in undissolved form which will dissolvein suiiicient amount in the oil during service to maintain'its resistance to oxidation and decomposition during service, without at any time causing a substantial excess of antioxidant tobe present in solution in the oil over that required to prevent oxidation. v

.11. A filter cartridge for internal combustion engine crankcase oil filters having replaceable filter elements, comprising a bed of packed fibrous filter medium having dispersed therethrough a slightly oil-soluble oil-improving agent in undissolved form which will dissolve in,the crankcase oil during service to inhibit decomposition thereof.

12.-A1nethod for purifying did inhibiting oxilet and outlet a. packed filtering medium havin dation and decomposition of a lubricating oil dursure of about 20 lbs. per sq. in and a temperature of about 200 .1.

14. The method of maintaining an effective concentration of a lubricatingoil addition agent in solution in lubricating oil during use in a lubricatingoil circulating system, which comprises contacting said oil with an organic additionagentsoluble in said oil in relatively low concentrations while circulating said oil through said lubricating 011 system.

- 15. The method of purifying engine lubricating oil and maintaining an efiective concentration 01 a lubricating oil addition agent in solution in'the oil during use in an lntemal combustion engine, which comprises passing said oil through a porous filtering material and contact- .30

ing the filtered oil with an organic addition a ent soluble in said oil in relatively low concentrations while circulating said 911 through the lubricating oil systemof. said engine.

16. Method according to claim 14 in which the lubricating oil addition agent is an oxidation inhibitor.

17. Method according to claim 14 in which the oil is contacted with the organic addition agent by passing the oil through a porous material having the lubricating oil addition agent dispersed therethrough. PHARIS MILLER. EUGENE LIEBER. 

